Former wartime enemies the United States and Vietnam extended into late Thursday talks on the communist country's bid to join the WTO, with the prospects for an imminent deal looking dim.

The talks between teams led by Dorothy Dwoskin, who heads WTO negotiations for the US Trade Representative, and Vietnamese Trade Minister Truong Dinh Tuyen began Tuesday and were due to have wrapped up after three days.

But a US official said they were still continuing late Thursday, and that no announcement would be made on their progress before Friday at the earliest.

It appeared that Vietnam's hopes of clearing the last major hurdle to its entry into the World Trade Organisation before it hosts a flagship summit later this year were unlikely to be met just yet.